Translation of the synaptonemal complex component Sycp3 is enhanced in vivo by the germ cell specific regulator Dazl

Abstract

DAZ-related genes are essential for gametogenesis in diverse metazoa: in human males, a loss of DAZ genes is associated with infertility. These genes, expressed only in germ cells, regulate the translation of a yet undefined set of specific transcripts, and loss of function results in numerous defects throughout the mitotic and meiotic process of germ cell development. In a mouse model, absence of the autosomal Dazl gene results in a final block at zygotene of meiotic prophase. Sycp3 is also essential for meiosis, specifically for the formation of the synaptonemal complex lateral element with a mouse knockout model displaying a block in meiotic prophase similar to the Dazl knock out. Sycp3 was identified as a potential target for translational regulation by Dazl in male mouse germ cells. This was confirmed by both RNA binding and translation assays. In the Dazl knockout mouse model, Sycp3 protein levels were decreased, indicating that Dazl is required for efficient translation of the Sycp3 mRNA in vivo. Taken together these data support Sycp3 as a biologically relevant target of Dazl-mediated translation in mammals. This suggests that azoospermia associated with a decrease in DAZ gene function in humans may in part be a consequence of failure at synapsis caused by reduced levels of SYCP3 protein.

Deleted in Azoospermia-Like Enhances In Vitro Derived Porcine Germ Cell Formation and Meiosis

“…Germ cells derived from Dazl knockout mice contain lower levels of MVH (VASA) protein, suggesting that the RNAbinding activity of the DAZL protein mediates regulation of Mvh translation in vivo [28]. A similar regulatory mechanism was also reported to control Scp3 expression, in which DAZL facilitates Scp3 translation by interacting with the 3¢UTR of the Scp3 transcript [17]. In our study, the expression of earlyand late-stage germ cell markers is also increased at the mRNA level in the DAZL-overexpressing group.…”

“…5D). As DAZL has been reported to enhance translation of SCP3 and VASA [17], we next sought to examine whether the levels of SCP3 and VASA were influenced by DAZL in our PLCs. Western blot analysis for DAZL, SCP3, and VASA was performed on total protein from PLCs collected at D36 of differentiation.…”

The DAZL and PABP families: RNA-binding proteins with interrelated roles in translational control in oocytes

“…Furthermore, the tethering of multiple molecules of DAZL stimulates translation to a greater extent than tethering of a single DAZL molecule; suggesting that multiple DAZL-binding sites may be required for efficient translational activation of an mRNA (Collier et al 2005). Consistent with this, several DAZL target mRNAs contain multiple DAZL-binding motifs (Reynolds et al , 2007 and identification of such 3 0 UTR motif clusters may prove important in identifying bona fide target mRNAs. While the DAZL-binding consensus occurs relatively frequently throughout vertebrate genomes; mRNAs with a 3 0 UTR that contains multiple binding sites occur much less frequently.…”

“…It is of note that this functional conservation occurs despite the relatively low sequence homology between some of these proteins outside the RRM and DAZ domains. Finally, the 3 0 UTRs from two potential mDAZL target mRNAs conferred DAZL-dependent translational regulation to reporter mRNAs, in microinjected X. laevis oocytes, and the levels of the protein products of these endogenous target mRNAs were reduced in the remaining germ cells in testis of mDazl null mice (see below; Reynolds et al , 2007.…”

Sex determination in mammalian germ cells: extrinsic versus intrinsic factors

“…Expression of Dazl seems to be necessary for correct methylation erasure of at least the H19 imprinted locus and for normal levels of expression of Ddx4 upon entry into the gonad (Reynolds et al 2005, Haston et al 2009. DAZL is known to bind the 3 0 -UTR of the Sycp3 transcript and positively regulate its translation (Reynolds et al 2007), so it would seem to make sense that DAZL-negative germ cells would have difficulty in progressing through meiosis. It is possible that DAZL works to affect translation of a number of germ line-and meiosis-specific transcripts.…”